Usually, a power circuit breaker contains two electrodes, to each of which, in operation, a respective pole of the voltage to be switched is applied. In particular when the electrodes are separated, there is a high likelihood that an undesired arc will occur. Even when this arc is extinguished in the meantime, there is the danger that it can reignite and indeed continue to do so until the separating gap is sufficiently large.
In order to ensure that such arcs are extinguished insofar as possible, the insulating gas SF6 (sulfur hexafluoride) is utilized in many known high-voltage power circuit breakers. However, this is a very strong greenhouse gas, which can escape into the atmosphere, particularly in the event of leakage and after the end of the service life.
Therefore, in particular for reasons of environmental compatibility, vacuum circuit breakers were developed for switching high voltages. In order to prevent arcing in vacuum circuit breakers, they are generally employed in alternating current systems. For alternating current, there is a periodic zero-crossing of the current, which is favorable to extinguishing the arc.
However, there is an increased need for the transmission of high-voltage direct current. Such systems of high-voltage direct current transmission (HVDC) have been proposed in current discussions by various parties on the energy transition and the expansion of the electrical grid, in particular for the connection of off-shore wind parks or the installation of coupling points. This is because direct current technology appears to be advantageous for higher powers given identical line widths, longer distances, and, above all, longer cable connections.
The reliable switching of high direct-current voltages is often realized by connecting a plurality of high-voltage power circuit breakers in series.
The European Patent EP 0 556 616 B1—or its German translation DE 693 02 716 T2—describes a direct current breaker arrangement that closes a commutating switch after interruption of a vacuum circuit breaker and transforms arcing direct current into an alternating waveform by means of commutation so as to end the interruption. This is intended to interrupt a direct current reliably so as to prevent any escalation of an operational malfunction.
The object of the present invention is to be able to switch an alternating current or direct current (or a corresponding power) in a simple and reliable way.